Housing, especially housing for containing a printed circuit board or the like, and method for producing the same

ABSTRACT

A housing ( 4 ) especially for containing electronic components or the like, includes a support element ( 1 ) provided with a borehole ( 12 ) for receiving a fixing screw ( 6 ), and a receptacle ( 14 ) which extends inside the housing and faces the borehole ( 12 ) for receiving the screw ( 6 ).

The present invention relates to a housing, in particular a housingintended to contain a printed circuit board (PCB) or the like, and to aprocess for obtaining it.

It is known practice, particularly in the field of electronics, to use ahousing within which electronic components are placed on a printedcircuit board. This housing comprises a lid which may, if appropriate,be formed by the printed circuit board. The lid is screwed onto thehousing so as to close the latter in a reversible manner. It is commonfor the screws used to be screws which themselves generate their tappedhole when being screwed in, such as self-tapping or thread-formingscrews. As the screws are being screwed in, flakes are produced and theydrop inside the housing, the screws being introduced from the outside ofsaid housing. The flakes thus produced often drop onto the printedcircuit board. They may then create a short circuit between the leads ofthe electronic components situated on the printed circuit board orbetween two tracks of this circuit board. A flake may thus render anelectronic device unusable.

Since the components are nowadays installed ever closer to one anotheron the printed circuit boards, the problems of short circuits created byflakes are increasingly frequent and are therefore becoming increasinglyinadmissible. It is thus an object of the present invention to provide ahousing which, by virtue of its design, prevents a flake from reachingthe printed circuit board intended to be accommodated within saidhousing. Preferably, the proposed housing does not entail anysignificant extra cost over a housing of the prior art.

To this end, the invention proposes a housing, in particular a housingintended to contain electronic components or the like, comprising asupport having a bore for receiving a fixing screw.

According to the invention, this housing additionally comprises, facingthe bore for receiving the screw, a receptacle extending inside thehousing.

In this way, the flakes formed when the screw is first screwed into itsbore are collected in the receptacle and are not able to contaminate theelectronic components inside the housing.

Preferably, the receptacle extends from the support having the bore and,with the exception of the region in which the bore is situated, forms aclosed space with this support. Once the screw is in place, the flakesare thus perfectly contained and are therefore unable to create anyshort circuits in the components.

The receptacle is, for example, obtained by stamping. In a preferredembodiment, it has a generally tubular shape of circular cross sectionwhich is closed at its end opposed to the bore.

The support originating from the housing and having the bore may takethe form of a lug folded over with respect to a wall of the housing. Thereceptacle is then, advantageously, borne by a tab folded onto the lug.

The present invention also relates to a cut and stamped sheet-metalblank, characterized in that it has:

-   -   a substantially rectangular lug attached by a first side,        substantially over its entire length, to the remainder of the        sheet-metal blank,    -   a bore made in the lug,    -   a tab connected to the lug by a side in the vicinity of the        first side, and    -   a receptacle obtained by a stamping operation performed on the        tab.

Such a sheet-metal blank makes it possible for a housing according tothe invention to be produced from a single piece of metal. To facilitateproduction of the housing, and particularly folding of the tab, asubstantially rectangular cutout is advantageously provided between thetab and the lug so as to form a hinge.

The present invention also proposes a process for producing a housing,in which a sheet-metal blank is cut and then folded, characterized inthat it comprises the steps which follow:

production of a sheet-metal blank as described above,

folding the tab flat onto the lug, and

folding the lug at a right angle with respect to the sheet-metal blank,

it being possible for the last two steps to be carried out in whateverorder.

Details and advantages of the present invention will become more clearlyapparent from the description which follows, given with reference to theappended schematic drawing, in which:

FIG. 1 is a partial view of a housing according to the invention in theregion of a fixing screw,

FIG. 2 is a view in section taken along the section line II-II of FIG.4,

FIG. 3 is a front view of the elements represented in FIG. 1,

FIG. 4 is a view taken along the section line IV-IV of FIG. 3,

FIG. 5 is a top view of the cut-out section of a sheet-metal blank forobtaining the portion represented in FIG. 1, and

FIG. 6 is a view in section taken along a section line VI-VI of FIG. 5.

FIG. 1 shows, viewed from below, the mounting of a lid 2 on a housing 4.The lid 2 may be a sheet-metal lid or one made of any other material, orelse it may also be a printed circuit board. The components fixed tothis printed circuit board are then oriented toward the inside of thehousing when this printed circuit board is fixed to the housing 4. Ascrew 6 can be seen in FIGS. 2 to 4 for keeping the lid 2 on the housing4. This screw is preferably a thread-forming screw which providesexcellent fastening without the use of a nut.

FIGS. 1 to 4 of the drawing show a portion of a side wall 8 of thehousing 4. The lid 2 is positioned perpendicularly to this side wall 8.To make it possible for the lid 2 to be mounted, the side wall 8comprises a lug 10 made in one piece with the side wall 8 and foldedover at a right angle to this wall toward the inside of the housing. Abore 12 for receiving the thread-forming screw 6 is made in this lug 10.Provision is made, in a known manner, for this bore to be of a smallerdiameter than the shank diameter of the screw 6. Thus, in a knownmanner, when the screw 6 is screwed into the bore 12 it deforms the lug10 around the bore 12 so as to form a tapped hole in the lug 10.

The lug 10 bears a receptacle 14. The latter is substantially circularcylindrical in shape and is tubular. It extends perpendicularly to theplane of the lug 10 (itself parallel to the lid 2). The receptacle 14rests on the lug 10. It is open toward this lug 10 and is closed at itsopposed end. The end wall 16, that is to say the wall situated away fromthe lug 10, is for example of hemispherical shape. The edge of thereceptacle on the side facing the lug 10 surrounds the bore 12 made inthis lug 10. The receptacle 14 thus creates a closed space whose onlyopening is the bore 12 and which is completely closed when a screw 6 issituated in this bore.

The receptacle 14 is formed on a tab 18 forming only a single piece withthe lug 10. This tab 18 is folded over at 180° with respect to the lug10. The tab 18 is joined to the lug 10 by two fine strips of metalforming a hinge 20. The receptacle 14 and its end wall 16 are obtainedfor example by stamping the tab 18.

The lug 10 and the receptacle 14 may advantageously form only a singlepiece with the wall 8 of the housing 4. It is possible by cutting,stamping and folding to obtain the lug 10 for mounting the screw 6 andthe receptacle 14 which acts as a flake trap for the flakes producedwhen the thread-forming screw 6 is screwed into its bore 12 for thefirst time. FIG. 5 shows, following cutting and prior to folding, thedetail of a metal sheet used for producing the housing 4 represented inFIGS. 1 to 4. This FIG. 5 depicts the wall 8, the lug 10 in which thebore 12 is made, and the tab 18 bearing the receptacle 14 and joined tothe lug 10 by the hinge 20. The lug 10 is attached to the wall 8. Thetab 18, for its part, is attached to the wall 8 only by way of the lug10 and the hinge 20. To produce said hinge, the sheet-metal blank usedfor producing the housing 4 has a rectangular cutout 22 separating thelug 10 from the tab 18. The stamping procedure forming the receptacle 14may be carried out immediately before cutting the metal sheet. Thisoperation is performed on the same press using an appropriate tool. Oncethe cutting operation has been carried out, two folding operations arecarried out successively. The tab 18 is folded through 180° about afirst folding axis 24 and then the assembly formed by the tab 18 and thelug 10 is folded through 90° about a second folding axis 26 so as to beturned toward the inside of the housing 4. It is thus possible,virtually without extra cost with respect to a conventional housingcomprising a lug but not a tab provided with a receptacle, to produce aflake trap which ensures that not a single flake resulting from thescrew 6 being screwed into the bore 12 will contaminate the electroniccomponents situated inside the housing 4. Any short circuit problemsbetween the leads of the components or the tracks of the printed circuitboard can thus be avoided. This is achieved without attaching anyadditional parts and virtually without extra cost with respect to thehousings of the prior art.

The present invention is not restricted to the preferred embodimentdescribed above by way of non-limiting example. It also relates to allvariant embodiments within the scope of a person skilled in the artwithin the framework of the claims hereinbelow.

Thus, for example, the lug 10 and the tab 18 are not necessarily placedon an edge of the side wall 8, but may be obtained at any point on saidside wall by forming a cut in said wall 8 over the periphery of theassembly formed by the lug 10 and tab 18, with the exception of the sideof the lug 10 corresponding to the second folding axis 26.

Furthermore, the shape of the receptacle may differ from that described.The process used to obtain it, for its part, may also be different. Inthis respect, a receptacle consisting of a part which is separate fromthe housing may be envisaged. For example, in the case of a housingwhose production requires welding operations, it may be envisaged toweld a part in the region of a bore intended to receive a thread-formingscrew so as to form the flake trap.

1. A housing (4), in particular a housing (4) intended to containelectronic components or the like, comprising a support (1) having abore (12) for receiving a fixing screw (6), characterized in that itadditionally comprises, facing the bore (12) for receiving the screw(6), a receptacle (14) extending inside the housing.
 2. The housing asclaimed in claim 1, characterized in that the receptacle (14) extendsfrom the support (1) having the bore (12) and, with the exception of theregion in which the bore (12) is situated, forms a closed space withthis support (1).
 3. The housing as claimed in claim 1, characterized inthat the receptacle (14) is obtained by stamping.
 4. The housing asclaimed in claim 1, characterized in that the receptacle (14) has agenerally tubular shape of circular cross section which is closed at itsend opposed to the bore (12).
 5. The housing as claimed in claim 1,characterized in that the support (1) having the bore (12) takes theform of a lug (10) folded over with respect to a wall (8) of thehousing.
 6. The housing as claimed in claim 5, characterized in that thereceptacle (14) is borne by a tab (18) folded over onto the lug (10). 7.A cut and stamped sheet-metal blank, characterized in that it has: asubstantially rectangular lug (10) attached by a first side,substantially over its entire length, to the remainder of thesheet-metal blank, a bore (12) made in the lug (10), a tab (18)connected to the lug (10) by a side in the vicinity of the first side,and a receptacle (14) obtained by a stamping operation performed on thetab (18).
 8. The sheet-metal blank as claimed in claim 7, characterizedin that it has a substantially rectangular cutout (22) produced betweenthe tab (18) and the lug (10) so as to form a hinge (20).
 9. A processfor producing a housing 4, in which a sheet-metal blank is cut and thenfolded, characterized in that it comprises the steps which follow:production of a sheet-metal blank as claimed in claim 7, folding the tab(18) flat onto the lug (10), and folding the lug (10) at a right anglewith respect to the sheet-metal blank, it being possible for the lasttwo steps to be carried out in whatever order.
 10. The housing asclaimed in claim 2, characterized in that the receptacle (14) isobtained by stamping.
 11. The housing as claimed in claim 2,characterized in that the receptacle (14) has a generally tubular shapeof circular cross section which is closed at its end opposed to the bore(12).
 12. The housing as claimed in claim 3, characterized in that thereceptacle (14) has a generally tubular shape of circular cross sectionwhich is closed at its end opposed to the bore (12).
 13. The housing asclaimed in claim 2, characterized in that the support (1) having thebore (12) takes the form of a lug (10) folded over with respect to awall (8) of the housing.
 14. The housing as claimed in claim 3,characterized in that the support (1) having the bore (12) takes theform of a lug (10) folded over with respect to a wall (8) of thehousing.
 15. The housing as claimed in claim 4, characterized in thatthe support (1) having the bore (12) takes the form of a lug (10) foldedover with respect to a wall (8) of the housing.
 16. A process forproducing a housing 4, in which a sheet-metal blank is cut and thenfolded, characterized in that it comprises the steps which follow:production of a sheet-metal blank as claimed in claim 8, folding the tab(18) flat onto the lug (10), and folding the lug (10) at a right anglewith respect to the sheet-metal blank, it being possible for the lasttwo steps to be carried out in whatever order.